Liquid crystal display and manufacturing method thereof

ABSTRACT

In an LCD, according to an embodiment of the present invention, a projection  6  is structured on top of insulation layer  8  on a TFT glass substrate  10  and under part of a black matrix  9 . The projection  6  encircles the transparent region in each pixel so that a spacer  17  cannot climb over the projection  6  and enter the transparent region even though a certain pressure is applied onto the substrates  10  and  11 . The width of the projection  6  is equal to or less than the diameter of the spacer  17 . The height of the projection  6  is equal to or longer than approximately 1% the length of the diameter of the spacer  17 , and it is preferable that it be equal to or longer than approximately 2%.

The present application is a Divisional Application of U.S. patentapplication Ser. No. 09/522,609 filed on Mar. 10, 2000 now U.S. Pat. No.6,760,089.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a liquid crystal display (LCD) and itsmanufacturing method.

2. Description of the Related Art

The TN (twisted nematic) mode is one of the current modes used for LCDdevices. In this mode, an electric field vertical to the surface of thesubstrate is used to orient the liquid crystal molecule director (themolecular major axis). By doing this, the optical transmittance iscontrolled so that an image can be displayed on the LCD panel. This is acommon type (hereafter called a vertical electric field driver-type) ofLCD device.

Since, with the vertical electric field driver-type LCD, the director isoriented to be vertical to the surface of the substrate when theelectric field is applied, the refractive index changes depending on theviewing angle. Accordingly, the vertical electric field driver-type LCDis not suitable when a wide viewing angle is needed.

There are also LCD devices where the liquid crystal director is orientedparallel to the surface of the substrate. These are devices where theelectric field functions in a direction parallel to the surface of thesubstrate so that the director can rotate in a plane parallel to thesurface of the substrate. Through this, the optical transmittance iscontrolled, and an image is displayed. This type (hereafter called alateral electric field driver-type) of LCD device has only just beendeveloped in recent years. With the lateral electric field driver-typeLCD, because the change in refractive index due to the viewing angle isremarkably small, a high quality display can be obtained.

An example of this type of lateral electric field driver-type LCD isshown in FIGS. 1 to 3. FIG. 1 is a plan view of a vertical electricfield driver-type LCD, FIG. 2 is a cross-sectional view of the LCD inFIG. 1 taken along the line JJ′, and FIG. 3 is a cross-sectional view ofthe LCD in FIG. 1 taken along the line KK′. The pixel shown in thesediagrams is formed of the following elements: a data line 1, a scanningline 2, a thin film transistor (TFT) 3, a common electrode 4 and a pixelelectrode 5. The scanning line 2 is connected to an external drivecircuit (not shown in the figures). The TFT 3 is a switching device. Thescanning line 2 and the common electrode 4 are both structured on asubstrate 10 where TFTs are fabricated (hereafter, called TFT substrate10). The pixel electrode 5 and the data line 1 are structured on thescanning line 2 and the common electrode 4 via an interlayer insulationfilm 7. The pixel electrode 5 and the common electrode 4 are alternatelypositioned. These electrodes are covered with a protection/insulationfilm 8. On the protection/insulation film 8, an alignment layer 15 islaid and subjected to a rubbing treatment.

A black matrix 9 to shield light is structured in a matrix format on theunderside of the opposite facing glass substrate 11. The primary andsecondary colored layers 12 and 13, which are necessary for colordisplay, are prepared on the black matrix 9. Each of the colored layers12 and 13 are assigned to each pixel. Here, the above two colorsrepresent two of the three primary colors: red, green, and blue. But,the one remaining colored layer is not shown in the figures.

On top of the primary and secondary colored layers 12, 13, anover-coating film 14 necessary to make the opposite facing substrate 11flat is prepared. An alignment layer 16, which will be necessary toorient the liquid crystal 18, is laid on the over-coating film 14 andthen subjected to a rubbing treatment. The rubbing treatment isperformed in the direction opposite to that performed on top surface ofthe TFT substrate 10.

Next, liquid crystal 18 and spacers 17 are poured into the gap betweenthe TFT substrate 10 and the opposite-facing substrate 11. The spacers17 are randomly distributed throughout the area between them. Theminimum distance between the two substrates determines the diameter ofthe spacers 17.

A polarizer film (not shown in the figures) is applied to the outersurface of the TFT substrate 10 where the electrode patterns have notbeen formed. This polarizer film is applied in a manner such that thetransmission axis runs in the direction perpendicular to the directionof the rubbing. A polarizer film (also not shown in the figures) isapplied to the outer surface of the opposite facing glass substrate 11where there are no layered patterns. The transmission axis of thepolarizer film on the opposite facing glass substrate 11 isperpendicular to the direction of the transmission axis of the polarizerfilm on the TFT substrate 10.

The LCD panel with the above structure is set up on a backlight andattached to a drive circuit.

In the above mentioned conventional LCD device, the liquid crystalpoured into the narrow gap between the TFT substrate and the oppositefacing substrate is normally oriented parallel to the direction that therubbing treatment was performed on the alignment layers 15 and 16. Asshown in FIG. 4, the liquid crystal molecules 20 surrounding each spacer17 are oriented parallel to the surface of the spacer 17. In this case,when the screen is in normally black mode (i.e. the mode where no lightcan pass through when no voltage is applied), light permeates throughthe area where the liquid crystal molecules are lined up askew to thepolarizer film absorption axis (for example, the liquid crystalmolecules in region 21). Due to this, a leakage of light develops in thefan blade-shaped regions 21. In addition, the weak aligning force causesthe alignment of the liquid crystal surrounding the spacers 17 to fallinto disorder. When this happens, the amount of leakage of light aroundthe spacers 17 increases; subsequently, as shown in FIG. 5, adoughnut-shaped region 21 of leakage of light develops.

Furthermore, when the liquid crystal panel happens to be impacted, thespacer 17 becomes charged by the friction created from being scrapedagainst the alignment layers on the TFT substrate and the oppositefacing substrate respectively. Once this occurs, a radial electric fielddevelops around the spacers 17. In this case, because the liquid crystalmolecules 20 become aligned parallel to the electric field, fanblade-shaped regions 21 of leakage of light develop, as shown in FIG. 6.

At this point, when comparing the two cases where the spacer 17 is notcharged as shown in FIG. 4 and where the spacer 17 has been charged upas shown in FIG. 6, it is apparent that the latter case gives largerradial areas of leakage of light 21.

This type of charging occurs when a certain pressure or impact, whichhappens to hit the LCD panel, causes spacers that are positioned in theopaque region of liquid crystal molecules (i.e., in the region ofcrystal molecules under the black matrix) to move and be strongly rubbedby the top surfaces of the alignment layers. This occurs easily sincethe gap at the opaque region (i.e., the region under the black matrix 9and on the data line 1, the scanning line 2, the TFT 3, etc.) isnarrower than the gap at the transparent regions, which widens thecontact area of the spacer with either surface of the alignment layers.The wider contact area allows a conveyance of a strong force, which iscaused by the certain pressure or impact being applied to the LCD panel,onto the spacer. This force can easily push and move the spacer out intoa transparent region of liquid crystal molecules. An electricallycharged spacer that has entered the transparent region increases thetotal amount of leakage of light, which in turn causes a deteriorationof display quality. On the other hand, a spacer that is originallypositioned within the transparent region of liquid crystal molecules israrely charged electrically by this type of movement since the gap ofthe transparent region is wider.

As described above, when a certain pressure or impact is applied to theLCD panel, the spacer that is positioned within an opaque region caneasily migrate to a transparent region and, especially when the LCDshows at all display area, an increase in leakage of light 21 becomesnoticeable. Besides, when the distribution of the spacers 17 is notuniform, the display quality becomes distorted and a problem developswhere the contrast decreases due to the leakage of light.

SUMMARY OF THE INVENTION

The present invention has been developed taking the above problems intoconsideration, comprising an active matrix LCD device and itsmanufacturing method, which have been made so that the amount of leakageof light is reduced and the degradation of display quality is preventedto avoid spacer's moving into a transparent region when the device isshaken or impacted.

According to an aspect of the present invention, an LCD with at leastone spacer (17) supporting two substrates that face each other isprovided and is comprised of at least one spacer (17) which ispositioned under an opaque region (9), and at least one projection (6,19) which is formed under the said opaque region (9), and on at leastone of the inner-most surfaces of a first and a second substrate. Anexample of the LCD is illustrated in FIG. 7.

According to an aspect of the present invention, an LCD with at leastone spacer (17) supporting two substrates that face each other isprovided and is comprised of at least one spacer (17) which ispositioned under an opaque region (9), and a broken line of projections(6, 19) which are formed on at least one of the inner-most surfaces of afirst and a second substrate so as to encircle a transparent region.

According to an aspect of the present invention, a method ofmanufacturing an LCD is provided and is comprised of the following stepsof depositing an insulation film (8) on a transparent substrate (10,11); etching off an area of the said insulation film 8 under an opaqueregion so as to form a ditch; and depositing an alignment layer (15) onthe resultant surface of the said insulating film (8). An example of themethod is illustrated in FIGS. 20 and 21.

BRIEF DESCRIPTION OF DRAWINGS

The above and other objects, features and advantages of the presentinvention will become more apparent from the following detaileddescription, when taken in conjunction with the accompanying drawings,wherein:

FIG. 1 illustrates a plan view of a conventional lateral electricfield-type LCD;

FIG. 2 illustrates a cross-sectional view of the conventional LCD takenalong a line JJ′ in FIG. 1;

FIG. 3 illustrates a cross-sectional view of the conventional LCD takenalong a line KK′ in FIG. 1;

FIG. 4 illustrates an enlarged schematic plan view of liquid crystalmolecules around the spacer in FIGS. 2 and 3;

FIG. 5 illustrates an enlarged schematic plan view of liquid crystalmolecules around the spacer in FIGS. 2 and 3;

FIG. 6 illustrates an enlarged schematic plan view of liquid crystalmolecules around the spacer in FIGS. 2 and 3;

FIG. 7 illustrates a plan view of an LCD, according to the firstembodiment of the present invention;

FIG. 8 illustrates a cross-sectional view of the LCD taken along a lineAA′ in FIG. 7;

FIG. 9 illustrates a cross-sectional view of the LCD taken along a lineBB′ in FIG. 7;

FIG. 10 illustrates a plan view of an LCD, according to the secondembodiment of the present invention;

FIG. 11 illustrates a cross-sectional view of the LCD taken along a lineCC′ in FIG. 10;

FIG. 12 illustrates a cross-sectional view of the LCD taken along a lineDD′ in FIG. 10;

FIG. 13 illustrates a plan view of an LCD, according to the thirdembodiment of the present invention;

FIG. 14 illustrates a cross-sectional view of the LCD taken along a lineEE′ in FIG. 13;

FIG. 15 illustrates a cross-sectional view of the LCD taken along a lineFF′ in FIG. 13;

FIG. 16 illustrates a plan view of an LCD, according to the fourthembodiment of the present invention;

FIG. 17 illustrates a cross-sectional view of the LCD taken along a lineGG′ in FIG. 16;

FIG. 18 illustrates a cross-sectional view of the LCD taken along a lineHH′ in FIG. 16;

FIG. 19 illustrates a plan view of an LCD, according to the fifthembodiment of the present invention; and

FIG. 20 illustrates a cross-sectional view of the LCD taken along a lineII′ in FIG. 19.

FIG. 21 is a flowchart showing process steps for structuring a ditchthat prevents each spacer from entering a transparent region.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

LCDs and their manufacturing methods, according to several embodimentsof the present invention, will be described with reference to thedrawings. These LCDs are structured so as to prevent spacers withinopaque regions of liquid crystal (e.g., areas of liquid crystal under ablack matrix), which support two substrates facing each other and allowthe liquid crystal to fill the space between them, from moving andentering a transparent region.

(First Embodiment)

FIG. 7 is a plan view of an active-matrix LCD, according to the firstembodiment of the present invention. FIG. 8 is a partial cross-sectionalview of the active-matrix LCD taken along a line AA′ in FIG. 7, whereasFIG. 9 is a partial cross-sectional view of the active-matrix LCD takenalong a line BB′ in FIG. 7.

As shown in these figures, a projection 6 is structured under part of ablack matrix 9 and on the glass substrate 10 where TFTs are fabricated(hereafter, called a TFT substrate), so as to encircle a transparentregion. The projection 6 prevents any spacer 17 positioned within thelight shielded regions of liquid crystal from entering the transparentregion. The projection 6 is positioned in the vicinity of a data line 1,a scanning line 2, or a TFT 3 on/above the TFT substrate 10, which havebeen structured under the black matrix 9 on the underside of the glasssubstrate 11.

As shown in FIG. 8, the projection 6, which is made of a metal pattern,is fabricated at a region overlapped with a part of the black matrix 9and also on a common electrode 4, which is positioned in the vicinity ofthe data line 1. The material of the projection 6 can be alternativelymade of a metal such as Cr, Al, or Mo, or an insulating material such asSiO₂ or SiNx. The formation of the projection 6 can be done during thefabrication of TFTs on the TFT substrate. Alternatively, the projection6 can be made of, for example, a resin and formed after the TFTs havebeen fabricated on the TFT substrate. An alignment layer 15 is thendeposited on the surface where the projection 6 has been fabricated.

The distance between the top surface of the alignment layer 15 over theprojection 6 and the undersurface of the alignment layer 16 on theopposite facing substrate 11 is shorter than that between the topsurface of the alignment layer 15 on the data line 1 and theundersurface of the alignment layer 16 under the opposite facingsubstrate 11. The width of the projection 6 is equal to or less than thediameter of the spacer 17. Namely, if the diameter of the spacer 17 isequal to 4 μm, the width of the projection 6 is equal to or less than 4μm.

Besides, as shown in FIG. 9; the distance between the top surface of thealignment layer 15 covering the projection 6 and the underside of thealignment layer 16 on the opposite facing substrate 11 is shorter thanthe distance between the top surface of the alignment layer 15 on theTFT 3 and the underside of the alignment layer 16 on the opposite facingsubstrate 11. The width of the projection 6 is equal to or less than thediameter of the spacer 17 in the same form as described above. Theprojection 6 can be made of a material identical to that of aprotection/insulation film 8 and formed by the following process: First,depositing a thick protection/insulation film 8 on the resultant surfaceincluding the surfaces of the data line 1, an interlayer insulation film7 and a scanning line 3 after TFTs have been fabricated; Secondly,selectively etching off a protection/insulation film 8 so as to leavethe area of the projection 6; Lastly, depositing the alignment layer 15over the entire resultant surface. The projection 6 can be alternativelymade of a material such as a resin and be formed by the followingprocess: First, depositing a protection/insulation film 8 on theresulting surface including the surfaces of data line 1, an interlayerinsulation film 7, and a scanning line 3 after TFTs have beenfabricated; Secondly, depositing any one of the materials for theprojection 6 as described above on top of the protection/insulation film8; Thirdly, selectively etching of the deposited material so as to leavethe area of the projection 6; Lastly, depositing the alignment layer 15all over the resultant surface. Afterwards, a plurality of spacers aredistributed throughout the resultant surface. The fabricated oppositefacing substrate, as illustrated in the upper area of FIGS. 8 and 9, isthen fixed on top of the multiple spacers, and liquid crystal 18 isinjected into the space between the two fabricated substrates.

The difference between the said distance from the top surface of thealignment layer 15 on the TFT 3, the data line 1 and the scanning line2, to the undersurface of the alignment layer 16 on the opposite facingsubstrate 11, and the distance from the top surface of the alignmentlayer 15 on top of the projection 6 to the undersurface of the alignmentlayer 16 on the opposite facing substrate 11 is equal to or longer thanapproximately 1% the length of the diameter of the spacer 17, and it ispreferable that it be equal to or longer than approximately 2%. In otherwords, the height of each projection 6 is equal to or longer thanapproximately 1% the length of the diameter of the spacer 17, and it ispreferable that it be equal to or longer than approximately 2%. Thisprevents each spacer 17 positioned within the opaque regions (i.e.,under the black matrix 9) from climbing over the projection 6 and thenentering a transparent region of liquid crystal molecules.

In summary, according to the first embodiment of the present invention,the projection 6 is structured on the TFT substrate 10, with thedistance between the top surface of the alignment layer 15 covering theprojection 6 and the underside of the alignment layer 16 on the oppositefacing substrate 11 being shorter than the distance between the topsurface of the alignment layer 15 on the data line 1, the scanning line2 and the TFT 3, and the undersurface of the alignment layer 16 on theopposite facing substrate 11.

Due to this structure, even if a certain pressure or impact happens tobe applied onto the LCD panel, it is difficult for any spacer 17, whichis positioned within the opaque regions or under the black matrix 9, toclimb over the projection 6, and then enter a transparent region;therefore, the leakage of light decreases, and the contrast is improved.Also, a possible unevenness in display quality due to the areas of theleakage of light being unevenly distributed is decreased. Furthermore,the panel becomes more durable against certain vibrations and impacts:Even if certain vibrations and impacts happen to hit the fabricatedactive-matrix LCD after it has been inspected, they cannot damage it. Asa result, high display quality is provided.

Incidentally, FIG. 7 illustrates a continuously extending projection 6positioned along the black matrix extensions. However, the presentinvention is not limited to this. Alternatively, the projection 6 can bemade up of multiple, intermittent pieces positioned along the extensionsof the black matrix 9. In other words, a broken line of projections canbe formed on the inner-most surface of the TFT substrate 10 so as toencircle the transparent regions. The length of each gap in the brokenline of projections is shorter than the diameter of the spacer 17.

(Second Embodiment)

Next, an LCD, according to the second embodiment of the presentinvention, will be described while referencing FIGS. 10 to 12. FIG. 10illustrates a plan view of the LCD of the second embodiment. FIG. 11illustrates a cross-sectional view of the LCD taken along a line CC′ inFIG. 10; whereas FIG. 12 illustrates a cross-sectional view of the LCDtaken along a line DD′ in FIG. 10.

In the LCD of the second embodiment, as shown in FIGS. 10 to 12, aprojection 19 is structured on the undersurface of an opposite facingsubstrate 11 under part of a black matrix 9, instead of on the topsurface on a TFT substrate 10, as in the first embodiment. During thefabrication of the opposite facing substrate 11, the projection 19 isstructured during the formation of the first colored layer 12 and anover-coating film 14. The projection 19 is made of a material identicalto that of a over-coating film 14, and can be formed by the followingprocess: First, depositing a thick over-coating film on the underside ofthe colored layers including the first and the second colored layers 12and 13, which have been deposited on the undersides of the black matrix9 and the opposite facing glass substrate 11; Secondly, selectivelyetching off the deposited film so as to leave the area of the projection19; Lastly, depositing the alignment layer 16 over the entire resultantsurface. The projection 19 can be alternatively formed by the followingprocess: First, depositing an over-coating film 14 on the underside ofthe colored layers including the first and the second colored layers 12and 13, which have been deposited on the undersides of the black matrix9 and the opposite facing glass substrate 11; Secondly, depositing amaterial for the projection 19 on top of the deposited over-coating film14; Thirdly, selectively etching off the deposited material so as toleave the area of the projection 19; Lastly, depositing the alignmentlayer 16 over the entire resultant surface of both the over-coating film14 and the projection 19.

Also, the projection 19 and the over-coating film 14, as shown in FIG.11, are simultaneously formed under the black matrix 9 on the oppositefacing substrate 11. The distance between the undersurface of thealignment layer 16 on top of the projection 19 and the top surface ofthe alignment layer 15 on the TFT substrate 10 is shorter than thatbetween the top surface of the alignment layer 15 on the data line 1 andthe undersurface of the alignment layer 16 on the opposite facingsubstrate 11. The width of the projection 19 is equal to or less thanthe diameter of the spacer 17. That is, if the diameter of the spacer 17is equal to 4 μm, the width of the projection 19 is accordingly equal toor less than 4 μm.

As shown in FIG. 12, the projection 19 is structured under part of theblack matrix 9 in the vicinity horizontal to the scanning line 2 and theTFT 3. The distance between the undersurface of the alignment layer 16on the underside of the projection 19 and the top surface of thealignment layer 15 on the TFT substrate 10 is shorter than that betweenthe top surface of the alignment layer 15 on both the scanning line 2and TFT 3, and the undersurface of the alignment layer 16 on theopposite facing substrate 11. The width of the projection 19 is equal toor less than the diameter of the spacer 17, as in the same format asdescribed above.

The difference between the distance from the top surface of thealignment layer 15 on the data line 1, the scanning line 2, and the TFT3, to the undersurface of the alignment layer 16 at the opposite facingsubstrate 11, and the distance from the undersurface of the alignmentlayer 16 on the underside of the projection 19 to the top surface of thealignment layer 15 at the TFT substrate 10 is, as is in the same formatas the first embodiment, equal to or longer than approximately 1% thelength of the diameter of the spacer 17, and it is preferable that it beequal to or longer than approximately 2%. In other words, the height ofeach projection 19 is equal to or longer than approximately 1% thelength of the diameter of the spacer 17, and it is preferable that it beequal to or longer than approximately 2%.

In summary, according to the second embodiment of the present invention,the projection 19 is structured on the opposite facing glass substrate11 with the distance between the undersurface of the alignment layer 16on the underside of the projection 19 and the top surface of thealignment layer 15 on the TFT substrate 10 being shorter than thatbetween the top surface of the alignment layer 15 on the data line 1,the scanning line 2, and the TFT 3, and the undersurface of thealignment layer 16 on the opposite facing substrate 11.

Due to this format, even if a certain pressure or an impact happens tohit the LCD panel of the second embodiment, it is difficult for anyspacer 17 positioned within the opaque regions (i.e., under the blackmatrix or on either the data line 1, the scanning line 2, or the TFT 3)to enter a transparent region. This prevents a possible increase inleakage of light caused by the entry of each spacer from occurring. As aresult, the leakage of light decreases, and the contrast is improved.Also, the uneven display resulting from areas of the leakage of lightbeing unevenly distributed is reduced. Furthermore, the panel becomesmore durable against certain vibrations and impacts: Even if certainvibrations and impacts happen to hit the fabricated, active-matrix LCDafter it has been inspected, they cannot damage it.

Incidentally, FIG. 10 illustrates a continuously extending projection 19positioned along the black matrix extensions. However, the presentinvention is not limited to this. Alternatively, the projection 19 canbe made up of multiple, intermittent pieces positioned along theextensions of the black matrix 9. In other words, a broken line ofprojections can be formed on the inner-most surface of the TFT substrate11 so as to encircle the transparent regions. The length of each gap inthe broken line of projections is shorter than the diameter of thespacer 17.

(Third Embodiment)

Next, an LCD, according to the third embodiment of the presentinvention, will be described while referencing FIGS. 13 to 15. In brief,the LCD of the third embodiment is attained by combining the structuresof the first and the second embodiment together. FIG. 13 illustrates aplan view of the LCD of the third embodiment. FIG. 14 illustrates across-sectional view of the LCD taken along a line EE′ in FIG. 13;whereas FIG. 15 illustrates a cross-sectional view of the LCD takenalong a line FF′ in FIG. 13.

According to the LCD of the third embodiment, as shown in FIGS. 14 and15, two independent projections 6 and 19 are structured on therespective TFT glass substrate 10 and opposite facing glass substrate11. The fabrication processes for the two projections 6 and 19 areidentical to those in the first and second embodiment.

As shown in FIG. 14, the projection 6, which is made of metal pattern,is structured under part of the black matrix 9, and on the commonelectrode 4 on top of the TFT substrate 10. On the other hand, theprojection 19 is structured to be part of the over-coating film 14 onthe opposite facing substrate 11, under the same part of the blackmatrix 9. The projections 6 and 19 on the respective TFT substrate 10and opposite facing substrate 11 face each other. The distance betweenthe top surfaces of the alignment layers 15 and 16 on top of therespective projections 6 and 19 is shorter than the distance between thetop surface of the alignment layer 15 on the data line 1 and theundersurface of the alignment layer 16 on the opposite facing substrate11.

With this format, the heights of the respective projections 6 and 19 canbe half of those of the respective first and second embodiments. Thewidths of the respective projections 6 and 19 are equal to or less thanthe diameter of the spacer 17 in the same format as the first and thesecond embodiment.

Incidentally, the present invention is not limited to the arrangement ofthe projections 6 and 19 facing each other and being positioned under apart of the black matrix 9. In other words, each of the projections 6 onthe TFT glass substrate 10 can be positioned far from each of theprojections 19 on the facing glass substrate 11 as long as they arepositioned under part of the black matrix 9, so as to prevent eachspacer 17 positioned under the black matrix 9 from climbing over andentering an optical transparent region. In this case, the distancebetween the top surface of the alignment layer 15 on top of eachprojection 6 and the undersurface of the alignment layer 16 on thefacing glass substrate 11, and the distance between the undersurface ofthe alignment layer 16 on top of each projection 19 and the top surfaceof the alignment layer 15 on the TFT glass substrate 10 should both beshorter than the distance between the top surface of the alignment layer15 on the data line 1 and the undersurface of the alignment layer 16 onthe facing glass substrate 11.

Due to the aforementioned arrangement of the projections 6 and 19 facingeach other, the number of the projections is doubled the number of thosein each of the first and the second embodiments. This prevents eachspacer positioned under the black matrix 9 from climbing over theprojections and entering a transparent region.

Next, other projections 6 and 19 positioned near a TFT 3 will bedescribed while referencing FIG. 15. As shown in FIG. 15, the projection6, which is made of a metal pattern, is structured under part of theblack matrix 9 and on the common electrode 4 formed near the scanningline 2 and TFT 3 on the TFT glass substrate 10. On the other hand, theprojection 19, which is made of the same material as that of theover-coating film 14, is structured under part of the black matrix 9 onthe undersurface of the opposite facing glass substrate 11, and is alsopositioned, in the horizontal direction, near the data line 1.

The projections 6 and 19 on the respective TFT glass substrate 10 andopposite facing substrate 11 face each other. The distance between thealignment layers 15 and 16 on the tops of the respective projections 6and 19 is shorter than the distance between the top surface of thealignment layer 15 on both the scanning line 2 and the TFT 3, and theundersurface of the alignment layer 16 on the opposite facing glasssubstrate 11. This allows the heights of the respective projections 6and 19 to be half the length of those of the first and the secondembodiment. The widths of the respective projections 6 and 19 are equalto or less than the diameter of the spacer 17 in the same format as thefirst and the second embodiment.

Incidentally, up to this point, it has been explained that theprojections 6 and 19 in FIG. 15 face each other. However, the presentinvention is not limited to this. Alternatively, each projection 6 canbe positioned not facing each projection 19. In this case, the distancebetween the top surface of the alignment layer 15 on top of eachprojection 6 and the undersurface of the alignment layer 16 on thefacing glass substrate 11 and the distance between the undersurface ofthe alignment layer 16 on top of each projection 19 and the top surfaceof the alignment layer 15 on the TFT glass substrate 10 should be bothshorter than the distance between the top surface of the alignment layer15 on both the scanning line 2 and TFT 3, and the undersurface of thealignment layer 16 on the facing glass substrate 1-1.

Due the structure of the projections 6 and 19 on the respective TFTglass substrate 10 and facing glass substrate 11, the total number ofprojections 6 and 19 is each double those of the first and the secondembodiment. This allows a surer prevention of each spacer 17 under theblack matrix 9 from entering an optical transparent region.

The difference between the distance from the top surface of thealignment layer 15 on the data line 1, the scanning line 2, and the TFT3, to the undersurface of the alignment layer 16 on the opposite facingsubstrate 11, and the distance from the undersurface of the alignmentlayer 16 on the underside of the projection 19 to the top surface of thealignment layer 15 on the TFT substrate 10 is, as is in the same form asthe first embodiment, equal to or longer than approximately 1% thelength of the diameter of the spacer 17, and it is preferable that it beequal to or longer than approximately 2%. Also, the difference betweenthe former distance and the distance between the top surface of thealignment layer 15 on top of the projection 6 and the undersurface ofthe alignment layer 16 at the opposite facing substrate 11 is equal toor longer than approximately 1% the length of the diameter of the spacer17, and it is preferable that it be equal to or longer thanapproximately 2%.

Due to this format described above, even if a certain pressure orimpulse happens to be applied onto the LCD panel of the thirdembodiment, each spacer 17 positioned under the black matrix and oneither the data line 1, the scanning line 2, or the TFT 3, is preventedfrom moving, climbing over, and entering a transparent region. Thisprevents a possible increase in the total amount of leakage of light dueto the entry of each spacer 17. As a result, the leakage of lightdecreases, and the contrast is improved. Also, the uneven displayresulting from areas of the leakage of light being unevenly distributedis reduced. These advantages allow the provision of an active-matrix LCDwith high reliability.

Incidentally, FIG. 13 illustrates continuously extending projections 6and 19 positioned along the black matrix extensions. However, thepresent invention is not limited to this. Alternatively, the projections6 and 19 can be made up of multiple, intermittent pieces positionedalong the extensions of the black matrix 9.

(Fourth Embodiment)

Next, an LCD, according to the fourth embodiment of the presentinvention, will be described while referencing FIGS. 16 to 18. In brief,the LCD of the fourth embodiment is attained by structuring differenttypes of projections on the TFT glass substrate 10 from the projections6 and 19 in the first to the third embodiments. FIG. 16 illustrates aplan view of the LCD of the fourth embodiment. FIG. 17 illustrates across-sectional view of the LCD taken along a line GG′ in FIG. 16;whereas FIG. 18 illustrates a cross-sectional view of the LCD takenalong a line HH′ in FIG. 16.

As shown in FIGS. 17 and 18, each of the aforementioned projections orbumps are structured by positioning a common electrode 4 on top of theTFT glass substrate 10. This causes the distance between the top surfaceof each bump caused by the common electrode 4, and the underside of theopposite facing glass substrate 11 to be shorter than the distancebetween the top surface of the alignment layer 15 on the data line 1,the scanning line 2, and the TFT 3, and the undersurface of thealignment layer 16 of the opposite facing glass substrate 11.

The difference between the distance from the top surface of thealignment layer 15 on the data line 1, the scanning line 2 and the TFT3, to the undersurface of the alignment layer 16 of the facing glasssubstrate 11, and the distance from the top surface of the bump on thecommon electrode 4 to the undersurface of the alignment layer 16 of theopposite facing glass substrate 11 is equal to or longer thanapproximately 1% the length of the diameter of the spacer 17, and it ispreferable that it be equal to or longer than approximately 2%. In otherwords, the height of each bump is equal to or longer than approximately1% the length of the diameter of the spacer 17, and it is preferablethat it be equal to or longer than approximately 2%. This allows theprevention of the spacer 17 from moving and entering an opticaltransparent region. In addition, each bump can be formed more easily bystructuring the common electrode 4 on the TFT substrate 10 thanstructuring the projections 6 and 19 according to the first throughthird embodiments. Accordingly, each bump can be fabricated by shortenedprocess steps.

Due to the form of the LCD of the fourth embodiment, even if a certainpressure or impulse happens to be applied onto the LCD panel, eachspacer 17 under the black matrix 9 and on either the data line 1, thescanning line 2, or the TFT 3, is prevented from moving and entering atransparent region. This prevents a possible increase in a total leakageof light due to each spacer 17. As a result, the displaying contrast isimproved. Also, the uneven display resulting from areas of leakage oflight being unevenly distributed is reduced. These advantages allow theprovision of an active-matrix LCD with high reliability.

(Fifth Embodiment)

Next, an LCD, according to the fifth embodiment of the presentinvention, will be described while referencing FIGS. 19 to 20. In thisembodiment, in place of forming each projection or bump, which preventseach spacer 17 within opaque regions (i.e., under the black matrix 9)from entering an optical transparent region, a ditch is formed on theinner surface of either the TFT glass substrate 10 or the facing glasssubstrate 11, so as to confine each spacer 17 within it, as shown inFIG. 20. FIG. 19 illustrates a plan view of the LCD of the fifthembodiment; whereas FIG. 20 illustrates a cross-sectional view of theLCD taken along a line II′ in FIG. 19.

In FIG. 20, the ditch where each spacer 17 is confined is formed on theinner surface of the TFT substrate 10 under the black matrix 9. As shownin the flowchart in FIG. 21, the ditch is formed by the followingprocess steps: First, a protection/insulation film 8 is deposited overthe surface of both the data line 1 and common electrode 4, which havebeen formed on top of the TFT glass substrate 10 (step S1); Secondly, anarea of the deposited protection/insulation film 8 under the blackmatrix 9, where at least one spacer 17 is later positioned, is etchedoff so as to form a ditch (step S2); Thirdly, interlayer insulation film7 is deposited onto the resultant surface (step S3); Fourthly, analignment layer 15 is deposited onto the resultant surface (step S4);Fifthly, a spacer 17 is placed within the resultant ditch (step S5);Lastly, the opposite facing substrate 11 with the black matrix 9,colored layers 12 and 13, over-coating film 14, and alignment layer 16,which have been arranged in the format as shown in FIG. 20, is fixedonto the spacers 17 so as to face the TFT glass substrate 10. With thisstructure, each spacer 17 in the ditch cannot go over the wall 22 of theditch, thus being confined within it.

The distance between the top surface of the alignment layer 15 on thecommon electrode 4 and the inner surface of the alignment layer 16 onthe opposite facing glass substrate 11 is shorter than the distancebetween the top surface of the alignment layer 15 on the signal 1 andthe inner surface of the alignment layer 16 on the facing glasssubstrate 11, as shown in FIG. 20. The difference between the formerdistance and the latter distance is equal to or longer thanapproximately 1% the length of the diameter of the spacer 17, and it ispreferable that it be equal to or longer than approximately 2%. Thisallows the prevention of the spacer 17 from moving and entering anoptical transparent region. As a result, even if a certain pressure orimpulse happens to be applied onto the LCD, each spacer 17 within the onditch is prevented from moving and entering a transparent region. Thisprevents an increase in total leakage of light around each spacer 17. Asa result, the uneven display resulting from areas of the leakage oflight being unevenly distributed is reduced. These advantages allow theprovision of an active-matrix LCD with high reliability and highdisplaying quality.

In the above description, the case where the ditch is formed at the TFTglass substrate 10 is explained. However, the present invention is notlimited to this. A ditch that confines each spacer 17 within it can benaturally formed on the opposite facing glass substrate 11.

Furthermore, in the above description, the case where the presentinvention is used for a lateral electric field-type/TFT active matrixLCD is explained. However, the present invention is not limited to this.The structure with the projections, the bumps, and the ditches asdescribed above, according to the present invention, can also benaturally used for the simple matrix TN(twisted nematic)- and STN(supertwisted nematic)-type LCD, the ferroelectric LCD, the polymer disbursedLCD, etc. The lateral electric field-type active matrix LCD, inparticular, often uses the normally black system (i.e., black isdisplayed while no voltage is applied), and may easily develop leakageof light due to the disarray in liquid crystal molecule orientationaround each spacer. This problem of leakage of light can be prevented byutilizing the aforementioned structures according to the presentinvention.

LCDs, and their manufacturing methods, according to the presentinvention, have been described in connection with several preferredembodiments. It is to be understood that the subject matter encompassedby the present invention is not limited to that specified embodiment. Onthe contrary, it is intended to include all alternatives, modifications,and equivalents as can be included within the spirit and scope of thefollowing claims.

1. A liquid crystal display (LCD), comprising at least one spacer whichis positioned under an opaque region, and at least one projection whichis formed under said opaque region, and on at least one of theinner-most surfaces of a first and a second substrate.